(1) Field of the Invention
The present invention generally relates to a bottom-lighting module, which provides backlight source to a display panel, and particularly relates to a bottom-lighting module with excellent heat sink ability.
(2) Description of the Prior Art
A Liquid Crystal Display (LCD) has been widely applied in notebook laptop, mobile phone, digital camera, video camera, PDA and other portable digital electronically products. Other than these small-sized portable products, the LCD inventing technology within large-sized products has been improved in great deal as well. For instance, desktop LCD monitor is replacing the traditional Cathode Ray Tube (CRT) monitor. LCD television with its light weight and reduced size, especially the thickness, are having huge competition with traditional television. A panel, or a liquid crystal panel, is an essential unit of the whole LCD. The panel itself does not generates light but modulates the transmittance of a backlight source, so as to present different gray levels. Hence, the backlight source is also an important element of the LCD. Among the various kinds of backlight source, a bottom-lighting module is usually implemented for larger-sized (such as bigger than 20′) LCD.
Referring to FIG. 1, it illustrates a cross section view of a prior bottom-lighting module. Within a LCD, a bottom-lighting module 10 is disposed right underneath a panel 12. The bottom-lighting module 10 includes a plurality of lamp 14, a diffuser plate 16 and a bezel 20. As shown in FIG. 1, in bottom-lighting module 10, light is provided by the plurality of lamp 14, which are arranged horizontally to each other and located underneath the panel 12. “Bottom-lighting module 10” thus picks up its name. The diffuser plate 16, located in between the plurality of lamp 14 and the panel 12, is needed for diffusing the light coming from beneath, so as to provide a more evenly distributed light to the panel 12. Above the diffuser plate 16, a plurality of optical film 18, such as a lower diffuser film, a lower brightness enhancement film, a upper brightness enhancement film and a upper diffuser film, is usually disposed to increase the overall light evenness and brightness.
Bezel 20, disposed underneath diffuser plate 16, includes a main body 201 and a plurality of inclined wall 203. For large-sized LCD, bezel 20 is usually made of metal material by punch machining processes. The plurality of inclined wall 203 supports the diffuser plate 16. The plurality of lamp 14 is disposed on the main body 201. However, because the plurality of lamp 14 is the main heat source of the bottom-lighting module 10, it is usually not in touch with the main body 201. Instead, lamp supporters (not shown in FIG. 1) are disposed to hold the plurality of lamp 14. Furthermore, in order to utilize the light generated by the plurality of lamp 14 more effectively, a reflecting plate (not shown in FIG. 1) is disposed on the surface of the bezel 20. Other times, applying light-reflecting materials on the surface of the bezel 20 is another typical prior arts, in same results, the light capable of being more effectively utilized.
The diffuser plate 16 and the bezel 20 shown in FIG. 1 often form a closed room-space. Ought to be thin enough to survive in the market, the thickness of the bottom-lighting module 10 is reduced as thin as possible, the above mentioned room-space meant to be very limited. As mentioned above, bottom-lighting module 10 is often used in large-sized LCD product, which needs relatively large amount of lamps 14 to present efficient brightness. Nevertheless, except generating light, the plurality of lamp 14 also serves as heat source in the bottom-lighting module 10. As a result, heat generated from these large amount of lamps 14 particularly tends to be accumulated in the closed room space and hardly to be removed.
While an LCD product is operated, especially exceeding a long period of time, the temperature could be increased dramatically over the area near lamp 14. This not only affects the function of LCD panel 12, causing the deterioration of display quality (i.e. some part of the displayed image turns out blurry and smudgy), but it could even decrease the life time of many kinds of internal element within the LCD product. As the tendency of the LCD products that: 1) growing to bigger sizes/scales; 2) improving displaying brightness both require more lamps 14 in a LCD product, an important challenge to the present technologies is to improve the heat sink ability of the bottom-lighting module, so as to enhance display quality, especially a remaining display quality, and to elongate the lifetime of all kinds of element in the LCD product.